Nile crocodile structure. African animals - crocodile. How long does a Nile crocodile live?
The Nile crocodile is an animal that people have revered and feared at the same time since ancient times. This reptile was worshiped in Ancient Egypt and mention of it as the monstrous Lephiathan is found in the Bible. It would be difficult in our time to find a person who would not know what a crocodile looks like, but not everyone knows what this reptile actually is, what kind of life it leads, what it eats and how it produces its offspring.
Description of the Nile crocodile
The Nile crocodile is a large reptile that belongs to the true family, living in Africa and being an integral link in aquatic and semi-aquatic ecosystems there. In size it exceeds most other crocodiles and is the second largest representative of this family after.
Appearance
The Nile crocodile has a squat body of a highly elongated format, which turns into a thick and strong tail, tapering towards the end. Moreover, the length of the tail can even exceed the size of the body. The strongly shortened powerful legs of this reptile are spaced widely - along the sides of the body. The head, when viewed from above, has the shape of a cone slightly tapering towards the end of the muzzle, the mouth is large, equipped with many sharp teeth, the total number of which can be 68 pieces.
This is interesting! In crocodile cubs that have just hatched from eggs, you can notice a skin thickening on the front of the muzzle that looks like a tooth. This seal, called an “egg tooth,” helps hatchling reptiles break through the shell and quickly emerge from their eggs.
The color of Nile crocodiles depends on their age: young individuals are darker - olive-brown with a cross-shaped black shading on the body and tail, while their belly is yellowish. With age, the skin of reptiles seems to fade and the color becomes paler - grayish-green with darker, but not too contrasting stripes on the body and tail.
The crocodile's skin is rough, lined with rows of vertical scutes. Unlike most other reptiles, the Nile crocodile does not shed, since its skin tends to stretch and grow along with the animal itself.
Sizes of the Nile crocodile
This is the largest of all crocodiles in Africa: the body length with tail in males of this species can reach five and a half meters. But, in most cases, Nile crocodile can hardly grow more than three meters in length. It is generally accepted that these reptiles grow from three to four meters in length, depending on their gender. The weight of a Nile crocodile can also range from 116 to 300 kg depending on its gender and age.
This is interesting! Some hunters, as well as residents of areas where Nile crocodiles live, claim that they have seen reptiles of this species, whose size reached seven or even nine meters. But due to the fact that these people cannot provide evidence of their meeting with such a monster, giant crocodiles than height exceeds five meters in length, are currently considered nothing more than a legend or even an invention of “eyewitnesses”.
Character and lifestyle
Under normal conditions, crocodiles are not very active animals.. Most of them, from morning to evening, either bask in the sun on the shores of reservoirs, with their mouths wide open, or are in the water, where they go after the midday heat begins. On cloudy days, however, these reptiles can remain on the shore until the evening. Reptiles spend their nights immersed in a river or lake.
This reptile does not like to live alone and, most often, Nile crocodiles settle in large groups, each of which can contain from several tens to several hundred animals of a given species. Sometimes they even hunt in a pack, although, usually, a crocodile hunts and prefers to act alone. Nile crocodiles can easily dive and swim underwater, which is helped by their physiological features: a four-chambered heart, like a bird’s, and a nictitating membrane, also called a membrane, which protects the animal’s eyes while it is immersed in water.
This is interesting! The nostrils and ears of Nile crocodiles have one very interesting feature: they close while the reptile dives. Nile crocodiles swim due to their powerful, oar-shaped tail, while they rarely use their paws, and even then only the hind ones, equipped with membranes, when swimming.
When getting onto land, these animals either crawl on their bellies or walk with their bodies raised. If desired or necessary, Nile crocodiles can even run, but they do this infrequently, only when chasing potential prey on land or when they are running away from another predator or from a rival that has defeated them. Nile crocodiles, although with difficulty, put up with the presence of their relatives nearby, but they treat animals of other species, with the possible exception of hippopotamuses, with whom they have an unspoken neutrality, extremely aggressively and fiercely defend their territory from the invasion of strangers, regardless of whether what species they belong to.
In the event of a climatic threat to their existence, such as extreme heat, drought or cold snap, Nile crocodiles can dig shelters in the ground and hibernate there until the situation outside returns to normal. But individual, very large reptiles are capable of waking up during this hibernation and crawling out to bask in the sun, and sometimes even to hunt, after which they return to their hole again and hibernate until their next foray outside.
Previously, there was a common belief that the crocodile had an unspoken alliance with certain species of birds, which help this reptile clean its mouth with their beaks, removing pieces of meat stuck between its teeth. But due to the fact that such evidence can hardly be considered reliable, these stories, like the stories about giant crocodiles 7-9 meters long, are considered to be nothing more than legends. In addition, it is difficult to say to what extent such different animals could interact and whether this relationship is a true symbiosis.
This is interesting! Interesting relationships develop between Nile crocodiles and those living in the same reservoirs as themselves. An unspoken neutrality has been established between these animals, but each of them does not miss the opportunity to take advantage of such a fortunate neighborhood for their own personal purposes.
It happens that female hippopotamuses, leaving their cubs for some time, leave them next to crocodiles, since toothy reptile, which none of them will dare to approach land predators, is the best possible protector for their children. In turn, the cubs of the Nile crocodile, while they are still small and very vulnerable, can also, during the absence of their mother, seek protection from hippos, while climbing on their backs.
Contrary to popular belief, crocodiles are far from mute: adults can make a sound similar to a bull's roar, and small cubs, recently hatched from eggs, croak like frogs and chirp, just like birds do.
How long does a Nile crocodile live?
Like most other reptiles, Nile crocodiles live quite a long time: their average lifespan is 45 years, although some of these reptiles live to be 80 years or more.
Sexual dimorphism
Males of this species are approximately one third larger in size than females, while the latter can be visually more massive due to the fact that their body proportions seem larger in girth. As for the coloring, the number of scutes or the shape of the head, Nile crocodiles of different sexes are almost the same.
Types of Nile crocodile
Depending on where Nile crocodiles live and on their external features.
Zoologists distinguish several types of this reptile:
- East African Nile crocodile.
- West African Nile crocodile.
- South African Nile crocodile.
- Malagasy Nile crocodile.
- Ethiopian Nile crocodile.
- Kenyan Nile crocodile.
- Central Farican Nile crocodile.
This is interesting! DNA analysis carried out in 2003 showed that representatives different populations Nile crocodile there are significant differences in terms of genotype. This gave some scientists a reason to distinguish populations of Nile crocodiles from Central and West Africa V separate species, called the desert or West African crocodile.
Range, habitats
The Nile crocodile is an inhabitant of continental Africa. You can find it everywhere south of the Sahara. It also lives in Madagascar and on some other, smaller islands located near the coast tropical Africa. As the name suggests, the Nile crocodile lives on the Nile, and is found everywhere, starting from the second river rapids and above.
This reptile is especially common in the countries of Southern and Eastern Africa, namely in Kenya, Ethiopia, Zambia and Somalia, where the cult of crocodiles is still popular. In former times, the reptile lived much further north - in the territory of Egypt and Palestine, but is no longer found there, since relatively recently it was completely exterminated in those parts.
The Nile crocodile chooses rivers, lakes, swamps, mangroves as its habitat, and this reptile can live in fresh water, and in salty. It tries to settle outside of forest areas, but sometimes wanders into forest reservoirs.
Diet of the Nile crocodile
The diet of the Nile crocodile undergoes dramatic changes throughout the life of this reptile. The cubs, which do not grow to 1 meter, mainly feed on insects and other small invertebrates. Of these, about half are various beetles, which small crocodiles especially like to eat. At night, the cubs can also hunt crickets and dragonflies, which they catch in the thick grass on the banks of ponds.
After the growing reptile reaches a size of one and a half meters, it begins to hunt crabs and snails, but as soon as it grows to 2 meters in length, the number of invertebrates in its menu is greatly reduced. And only in Uganda alone, even fully grown crocodiles rarely, but still eat large snails and a variety of freshwater crabs.
Fish appears in the diet of a young Nile crocodile after it grows to at least 1.2 meters, but at the same time it continues to feed on invertebrates: large insects, crabs and mollusks like snails.
Important! It is fish that is the main food of adolescents of this species, and in some places, for the most part, it is also what adults feed on, which have not yet reached a length of three meters.
At the same time, the reptile tries to hunt fish that match its size. A large crocodile will not chase in the river for small fish, and, first of all, this is due to the fact that it is much more mobile than, for example, the rather large catfish, which the rather large Nile crocodile prefers to feed on.
But it would be wrong to think that Nile crocodiles eat tens of kilograms of fish at a time: reptiles, characterized by low mobility, require significantly less food than warm-blooded animals, and therefore, a reptile weighing less than 120 kg, on average, eats only 300 grams of fish. Due to the fact that there are a lot of crocodiles in African rivers, there is a natural regulation of the number of fish species living in the same lakes, rivers and other bodies of water as these reptiles, but no significant damage is caused to their population.
Crocodiles can also prey on amphibians and other reptile species. At the same time, adult frogs do not eat, although growing young animals feed on them with pleasure. And among reptiles, Nile crocodiles even eat poisonous snakes, such as . and some especially large lizards, such as the Nile monitor, are also eaten by adult animals. Young crocodiles also try to hunt turtles, but due to the fact that until a certain age they do not have enough strength to bite through a turtle shell, such a hunt could hardly be called successful.
But birds are rarely found on the crocodile menu and, in general, make up only 10-15% of total number food eaten by the reptile. Most birds become victims of crocodiles by accident, as, for example, happens with fledgling cormorant chicks that accidentally fall from the nest into the water.
Large adult individuals, whose size exceeds 3.5 meters, prefer to hunt mammals, mainly ungulates, which come to a river or lake to drink. But even young animals that have reached a length of 1.5 meters can already begin to hunt mammals of not too large sizes, such as small monkeys, small species of antelope, rodents, lagomorphs and the bats. Their menu even includes such exotic things as pangolins, also called pangolins, but not related to reptiles. Small predators, such as civets, can also become a victim of a growing crocodile.
Adult crocodiles prefer to hunt larger game, such as kudu, eland, buffalo, and giraffe.
Nile crocodiles have also been observed eating livestock and people. If you believe the statements of the inhabitants of African villages, then several people are necessarily dragged away and eaten by crocodiles once a year. To conclude the topic regarding the diet of reptiles of this species, we can also add that Nile crocodiles were also observed in cannibalism, when adults ate the eggs of their relatives or cubs of their own species, in addition, this reptile is quite capable of eating an opponent killed in battle.
The most ancient animal, living since the time of dinosaurs, is the crocodile. And most dangerous species are considered Nile and saltwater crocodile. It is on account of these animals greatest number human casualties.
In this article we will talk about the Nile crocodile.
It is found throughout the Seychelles and Comoros Islands, Madagascar. Relatively recently, it could still be found in Asia, but today it is completely exterminated there. Nile crocodiles divided into a large number of types:
These are found in rivers and freshwater. They can reach a length of 4 to 6 meters, but giants with a length of 7 meters are also known. These animals can weigh from 270 to 910 kg.
From the photographs it can be seen that Nile crocodiles do not have a very long muzzle, which does not exceed its width. Young animals are brown and also dark olive in color. An adult crocodile is dark green in color with black spots on its back, and its belly is lighter than the rest of the animal's body, often a dirty yellow color. With age, the reptile becomes more and more pale.
The nostrils and eyes of crocodiles are located at the top of the head, which is why they can breathe and see when the rest of the body is in the water. Unlike other animals, these reptiles have external ears that close like the nostrils when crocodiles dive.
The Nile crocodile is a diurnal animal. During the night they lie down in bodies of water, and when the sun rises, they go hunting, or continue to rest in the sun.
Nutrition and hunting of the Nile crocodile
The Nile crocodile eats quite varied. Small reptiles feed on, for example, dragonflies. More large crocodiles– shellfish, fish, and crustaceans. Sometimes their prey is a bird, a reptile, or a mammal such as a rhinoceros or buffalo. Sometimes animals attack lions and tigers.
The reptile waits for its future victim in the water, near the shore. It may take more than one hour until something living approaches the water. Then the reptile swims closer to the prey and waits at a distance of about several meters, at which time its body is immersed in water, with the exception of the eyes and nostrils. Suddenly, the reptile jumps out of the water and grabs the victim's head with its mouth, drowning it, dragging it into deep water. Then, with the help of its powerful jaws, the crocodile tears out parts of the meat.
When hunting fish, the reptile hits its tail to stun and frighten it, and the one that is stunned is swallowed. Reptiles feed quite often, although they can go without food for several days, sometimes a year or even more.
Crocodiles are remarkably adapted to living underwater and in the water. They use their paddle-like, powerful tail to swim. The hind legs are webbed. Another adaptation to aquatic life is the presence of a third eyelid: a membrane that, when immersed under water, protects its eyes, while the crocodile can see further. Crocodiles can stay under water for a very long time: on average, about forty minutes, and older crocodiles may not surface for more than one hour.
Of course, on land reptiles are slower than in water, but they still develop a fairly good speed of 30 km/h. But the most interesting thing is that on land crocodiles are very cowardly and do everything possible to run away to the water as quickly as possible. It is for this reason that only about 3 out of 10 reptile attacks occur on land.
Reproduction of Nile crocodiles
Crocodiles become ready to reproduce only at 8-12 years of age. A female individual lays 50 eggs. Throughout the entire incubation period, a period of 80-90 days, she remains close to the nest, then provides assistance to the newborns in getting out of the nest. Young crocodiles live with their mother for two years.
CROCODILE
Squad CROCODILES(Crocodylia) - a family of reptiles. There are three species living in Africa. The narrow-snouted crocodile is endemic to Africa. Lives in everyone large rivers West Africa, Lake Tanganyika and the east of the mainland. Blunt (or dwarf) crocodile - in central Africa. Nile crocodile - on the mainland and some islands.
Crocodiles occupy special position among modern reptiles, being closer relatives of extinct dinosaurs, which survived by almost 60 million years, and modern birds than other reptiles of our time. A number of features of the organization of crocodiles, and first of all the perfection of the nervous, circulatory and respiratory systems, allows us to consider them the most highly organized of all living reptiles. The evolution of crocodiles, starting with the appearance of this group about 150 million years ago, went in the direction of increasing adaptation to the aquatic lifestyle and predation. The fact that crocodiles have survived to this day is often explained by their life in various fresh water bodies of the tropical and subtropical zones, that is, in places where conditions have changed little since the appearance of crocodiles.
The general body shape of the crocodile is lizard-shaped. They are characterized by a long, laterally compressed, high tail, membranes between the toes of the hind limbs, long muzzle and a head flattened in the dorso-ventral direction. The forelimbs have five fingers, the hind limbs have four (there is no little finger). The nostrils, located at the front end of the muzzle, and the eyes are raised and located on the upper side of the head, which allows crocodiles to stay in the water near its surface, exposing only the eyes and nostrils to the air. The external auditory openings are closed with movable valves that protect the eardrums from mechanical damage when immersed in water. The body, tail and limbs of crocodiles are covered with large, regular-shaped horny scutes located on the back and stomach in regular rows. In the inner layer of skin (corium) under the horny scutes of the outer layer on the back and in some species on the belly, bone plates (osteoderms) develop, firmly connected to the horny scutes, forming a shell that well protects the crocodile’s body; on the head, osteoderms are fused with the bones of the skull.
Modern crocodiles inhabit various fresh water bodies. Relatively few species tolerate brackish water and are found in river estuaries (African narrow-snouted crocodile, Nile crocodile, American sharp-snouted crocodile). Only the saltwater crocodile swims far into the open sea and has been observed at a distance of 600 km from the nearest shore. Most Crocodiles spend days in the water. They go out to the coastal shallows in the morning and in the late afternoon to warm up in sun rays.
Crocodiles hunt at night. Fish is an essential component of the diet of all crocodiles, but crocodiles eat any prey they can handle. Therefore, the set of foods changes with age: various invertebrates - insects, crustaceans, mollusks, worms - serve as food for the young; larger animals hunt fish, amphibians, reptiles and aquatic birds. Adult crocodiles are able to cope with large mammals. There is a known case of the remains of a rhinoceros being found in the stomach of a Nile crocodile. Many species of crocodiles exhibit cannibalism - the devouring of smaller individuals by larger individuals. Crocodiles often eat carrion; some species hide the uneaten remains of the prey under an overhanging bank and later devour them half-decomposed. Crocodiles move in the water with the help of their tail. On land, crocodiles are slow and clumsy, but sometimes make significant journeys, moving several kilometers away from bodies of water. When moving quickly, crocodiles place their legs under their body (usually they are widely spaced), which rises high above the ground. Young Nile crocodiles can gallop at a speed of about 12 km per hour. Crocodiles lay eggs the size of chicken or goose eggs, covered with a calcareous shell. Number of eggs in clutch different types there are from 10 to 100. Some species bury their eggs in the sand, others lay them in nests made by the female from rotting vegetation. The female remains close to the clutch, protecting it from enemies. Young crocodiles, still inside the eggs, make croaking sounds at the time of hatching, after which the mother digs up the clutch, helping the offspring get out.
Crocodiles grow rapidly in the first 2-3 years of life, during which they reach crocodiles and gharials. sizes 1-1.5 m. With age, the growth rate decreases, and they add only a few centimeters in length per year. They reach sexual maturity at the age of 8-10 years. Crocodiles live up to 80 - 100 years. Adult crocodiles have few enemies, if you exclude humans. There have been cases of attacks by elephants and lions on crocodiles traveling overland from one body of water to another.
Widely distributed in Africa Nile Crocodile(Crocodylus niloticus). It can be found throughout Africa, except its northern part, in Madagascar, Comoros and Seychelles. Most often it settles outside the forest, but also enters forest reservoirs. Reaches a length of 4-6 m. The cubs that have just hatched from eggs have a length of about 28 cm, by the end of the first year of life they reach 60 cm, by two years - 90 cm, at 5 years - 1.7 m, at 10 years - 2, 3 m and at 20 years old - 3.75 m. They spend the night in the water, and at sunrise they go out to the shallows and bask in the sun's rays. The midday, hottest hours are spent in the water, with the exception of cloudy days. When it's windy, inclement weather spend the night on the shore. The maximum duration of stay under water for animals about 1 m long is about 40 minutes; larger crocodiles can stay underwater for much longer. The food of the Nile crocodile is very varied and changes with age. In cubs up to 30 cm long, 70% of their food consists of insects. Larger individuals (about 2.5 m long) feed on fish, mollusks, crustaceans, and even larger ones feed on fish, reptiles, birds and mammals. Adult Nile crocodiles can attack large mammals such as buffalos and even rhinoceroses. Crocodiles lie in wait for animals near watering places, in water or on land in thick grass. In a number of areas, Nile crocodiles are dangerous to humans. Eggs are always laid in the dry season, when water levels are low. Females dig a hole in the sand up to 60 cm deep, where they lay 25-95 (on average 55-60) eggs. Incubation lasts about 90 days, during which the mother remains constantly at the nest, guarding the clutch. Apparently, the animal is not feeding at this time. By the time they hatch, the young crocodiles inside the eggs begin to make grunting sounds, which serve as a signal for the mother, who helps the cubs get out from under the sand and accompanies them to the water. At this time, the female can attack a person even on land. Hatching from eggs usually occurs after the first rains fall, with a rise in the water level in lakes and rivers, so that young crocodiles immediately find shelter and food in flooded reservoirs. After the young crocodiles emerge from the eggs, the mother leads them (according to Cott's observations) to the “nursery” she has chosen - a shallow body of water protected by vegetation. Here young crocodiles stay for about six weeks; all this time the mother remains with the brood, protecting it from attacks by predators. In the absence of a mother, crocodiles hatched from eggs often remain close to the nest, where they are usually exterminated by predators - goliath herons, marabou, kites. Numerous cases of cannibalism (devouring eggs and young individuals) are known, which is usually considered a mechanism for regulating the population of the species: it is noted that cannibalism occurs more often, the higher the number of crocodiles. The number of Nile crocodiles has fallen everywhere and continues to fall. IN ancient Egypt crocodiles were revered as sacred animals; now they are almost exterminated. The same fate will befall crocodiles in a number of places in Central and Eastern Africa if measures are not taken to protect the species
The Nile crocodile (lat. Crocodylus niloticus) is a large reptile of the family of true crocodiles. The largest of the 3 species of crocodiles found in Africa, and the second largest in the world after the saltwater crocodile. Due to its habitat, size and strength, it is known as a man-eating crocodile and was an object of fear and worship in ancient times. To this day it remains perhaps the most known species crocodiles. In general, the species' numbers are relatively high and stable, although populations in some countries are endangered.
Appearance
Like all crocodiles, the Nile crocodile has short legs located on the sides of the body, scaly skin covered with rows of bony plates, a long strong tail and powerful jaws. The crocodile's eyes are equipped with a third eyelid for added protection and have special glands that allow them to be washed with tears (hence the expression "crocodile tears"). The nostrils, ears and eyes are located at the top of the head, thanks to which the crocodile can almost completely submerge in water, leaving them on the surface.
The coloring of the Nile crocodile also allows it to remain undetected. Juveniles are usually gray or light brown with dark stripes on the back and tail. With age, the color darkens and the stripes become less noticeable. The belly has a yellow tint; this skin is considered to be of the highest quality.
Usually the crocodile crawls on its stomach, but can also walk with its body raised. Small individuals are able to run a short distance at a gallop, developing a speed of 12-14 km/h. It also swims quickly (30 km/h) making sinusoidal movements with its tail.
Physiology
The heart is four-chambered, like a bird's, which allows it to oxygenate the blood more efficiently. Typically, the Nile crocodile dives for 2-3 minutes, but if necessary, it can remain under water for up to 30 minutes, and with reduced activity - up to two hours. Being a cold-blooded animal, it has a relatively slow metabolism and can for a long time can do without food, but at the same time is able to eat up to half of its own weight in one sitting.
The Nile crocodile has fairly good hearing and a rich vocal range. Its skin is equipped with special receptors that respond to changes in water pressure. The jaws have impressive strength, which allows them to hold large animals. Typically has 64-68 conical teeth - 36-38 on the upper jaw and 28-30 on the lower jaw. Newly hatched crocodiles have a special tooth-like seal of skin at the front of their snout that helps them escape from the egg.
Dimensions
The Nile crocodile is large in size, usually about 5 m, occasionally up to 5.5 m. Weight often exceeds 500 kg, and there are individual specimens weighing over 1200 kg. The largest known specimen was killed in Tanzania in 1905: length 6.45 m, weight 1090 kg. Reports of 7-meter crocodiles have not been confirmed. On southern border range - in South Africa several Nile crocodiles smaller in size, their length usually does not exceed 4 m. Like other species of crocodiles, they exhibit sexual dimorphism - females are on average 30% smaller than males. Overall the differences are smaller than in many other species.
Crocodiles living in colder climates, such as southern Africa, are smaller - about 4 m. The dwarf Nile crocodile, living in Mali and the Sahara Desert, grows only to 2-3 m. It is believed that such differences in size are a consequence of worse living conditions, and not genetic differences.
Reproduction
IN normal conditions The Nile crocodile becomes sexually mature by the age of ten, when it reaches a length of 3 m for males, 2-2.5 m for females. During the mating season, males attract females by slapping the water with their snouts, roaring, snorting and making other noises. Large males are usually more attractive to females. During mating games, couples “sing” peculiar trills and rub the undersides of their muzzles.
The time of egg laying largely depends on latitude - in the north of the range it occurs during the dry season, and in the south it is usually tied to the beginning of the rainy season - November or December. In Zimbabwe, females lay eggs in September or early October. Favorite places for building nests - sandy beaches, dry riverbeds and river banks. The female digs a hole up to 50 cm deep two meters from the shore and lays from 20 to 85 eggs (50 on average). Several females may build nests close to each other.
Having laid eggs, expectant mother covers the nest with sand and guards it during the 3-month incubation period. The father is usually nearby too, and both parents will attack anyone who tries to approach the nest. Despite such care, many nests are destroyed by people, monitor lizards and other animals if the mother leaves to hide from the heat or take a dip in the water.
The hatchlings make chirping sounds, and at this signal the mother breaks the nest. Parents sometimes take the eggs into their mouths and squeeze them between the tongue and roof of the mouth to help the offspring release. Then the female takes the crocodiles to the water or carries them in her mouth.
As with other crocodiles, the sex of the young is determined by temperature during the middle third of the incubation period, rather than genetically. If the temperature inside the nest was below 31.7 °C or above 34.5 °C, then females are born, otherwise - males.
Newly hatched crocodiles are about 30 cm long and grow quite quickly in the first years. The mother takes care of the offspring for two years. If several nests were close to each other, mothers can jointly care for their offspring, forming a kind of crocodile nursery. Within two years, young crocodiles reach a size of 1.2 m and leave their native places, while avoiding the territories of older and larger crocodiles. Average duration The lifespan of Nile crocodiles is 45 years; there are specimens up to 80 years old.
Nutrition
Newly hatched crocodiles feed on insects and aquatic invertebrates, quickly switching to amphibians, reptiles and birds. The diet of even adult crocodiles consists of 70% fish and other small vertebrates, despite the fact that a crocodile can eat almost any animal that comes to a watering hole, with the exception of adult elephants and hippos. The Nile crocodile also eats carrion, although it avoids rotten meat. A group of crocodiles can go hundreds of meters from the shore to get to the carcass of a large animal.
An adult crocodile uses its body and tail to push a school of fish towards the shore and eats it with a quick movement of its head. Crocodiles can also form a group and block migrating fish by forming a semicircle across the river. In this case, dominant crocodiles eat first.
It is known that Nile crocodiles can successfully attack zebras, antelopes, buffalos, young hippos and rhinoceroses, giraffes, warthogs, hyenas, monkeys, felids, as well as other crocodiles. The ability to almost completely hide under water in combination with high speed makes crocodiles at short distances good hunters for large prey. They grab her with powerful jaws, drag her into the water and hold her there until she drowns. When the prey is dead, they tear off pieces of it and swallow it. When sharing joint prey, they coordinate efforts to tear the body apart, and can also push it under snags or stones for this purpose.
The Nile crocodile poses a danger to humans, although to a lesser extent than the saltwater crocodile. Females are especially dangerous during the period of caring for offspring, when they become especially aggressive towards any animal approaching the nest. Most attacks occur far from civilization and are not recorded, so the actual number of victims is unknown. According to some sources, it is 1000 people per year, according to others - 200. In 2005, a crocodile was caught in Uganda, which, according to statements local residents, ate 83 people in 20 years. In 2006, Richard Root, a professor of medicine at the University of Washington, fell victim to a crocodile in Botswana.
The Nile crocodile is believed to have a symbiotic relationship with some birds, such as the clawed lapwing (Vanellus spinosus). According to some reports, the crocodile opens its mouth wide, and at this time the bird takes out pieces of meat stuck in its teeth. However, these reports have proven difficult to verify, and it may not be a truly symbiotic relationship.
Distribution and protection
The Nile crocodile prefers to live along the banks of rivers and lakes and in freshwater swamps, and is sometimes found in brackish water, estuaries or mangroves. It is distributed throughout almost all of sub-Saharan Africa, as well as in Madagascar and the Nile Basin. It once lived much further north - fossil remains of this animal were discovered in Algeria, Israel and Jordan, as well as on the Comoros Islands.
From the 1940s to the 1960s, the Nile crocodile was heavily hunted, mainly for its high-quality skin, less so for its meat and supposed organs. medicinal properties. This led to a multiple reduction in the number of the species, resulting in the threat of its extinction.
The Nile crocodile is widespread in many countries of southern and East Africa, such as Somalia, Ethiopia, Kenya, Zambia, the population size is monitored and documented.
The Nile crocodile is included in the Red List World Union nature protection in the category of minimal risk. The crocodile trade is regulated international convention according to Appendix I of CITES.
Crocodylus niloticus) - a large reptile animal from the order of crocodiles, the family of crocodilians, the genus of the true.
The Nile crocodile is the most common member of the family, the largest African crocodile and the second largest giant reptile in the world, second only in size to the saltwater crocodile.
The main food of an adult Nile crocodile is various small and large mammals: , cane rats, otters, bush cats, civets, . Big booty become different kinds(waterbucks, impalas, kudu, gazelles), large forest aardvarks, aardvarks, African manatees, as well as all types of domestic animals that accidentally wandered into a watering hole. The largest Nile crocodiles attack buffaloes, cubs and, brown hyenas and big cats.
Nile crocodiles also eat carrion, steal food from hyena dogs, etc. U predatory reptile slow metabolism, so the animal can starve for a long time, but with a successful hunt, the volume of food consumed at a time can be up to 20% of its own weight, and crocodiles feed at every opportunity. Only female Nile crocodiles, guarding their nests, eat little.
Reproduction of Nile crocodiles
Sexual maturity of Nile crocodiles occurs at 12-15 years of age, when males grow to 2.5-3 m, and females up to 2-2.5 m in length. Offensive mating season depends on the habitat: Northern part The population breeds in the summer, and individuals living in the south breed during the rainy season - in November and December.
During the rut, special, hierarchical relationships are established among sexually mature males of the Nile crocodile. Quite aggressive clashes often occur between representatives of the species, in which males demonstrate their superiority over their opponent. Crocodiles exhale noisily through their mouths, make growling or grumbling-like sounds, and blow bubbles with their open mouths. Simultaneously with these demonstration actions, Nile crocodiles, excited by the fight for the future female, bend their necks, raise their tails, whipping them on the surface of the water. Having admitted defeat, one of the males turns around and high speed swims away, trying to escape the pursuit of a competitor. If it is not possible to escape, the losing crocodile raises its head high, opening access to its throat: this position is a sign of peace and recognition of defeat. The winning crocodile sometimes grabs one of the opponent's limbs with its jaws, but does not bite it. Such “prenuptial” fights make it possible to expel extra males from the territory favored by a pair of crocodiles.
During the breeding season, males behave quite unusually and interestingly: they roar invitingly, snort loudly, slap their muzzles in the water and try in every possible way to attract females, with females preferring the largest males. Mating games consist in singing peculiar trills, during which partners open their mouths wide and rub the lower surfaces of their muzzles.
Sandy beaches and shallows, dry riverbeds and river banks become places for laying eggs. Near the water's edge, the female Nile crocodile digs a nest up to 60 cm deep and lays 20 to 95 eggs (usually around 55-60). The female vigilantly guards the buried clutch throughout the entire incubation period, which is approximately 90 days. Periodically, the male helps her, and the couple fights back against anyone who poses a threat to the offspring. Occasionally, the female is forced to hide from the heat, and the nest of the Nile crocodile left unattended is destroyed by mongooses, spotted hyenas, baboons and people. Sometimes nests built in the wrong place suffer from floods. In total, only 10-15% of eggs survive to the end of incubation.
Taken from www.africawildtrails.com
Newborn crocodiles make grunting sounds, which becomes a signal for the female: she digs up the nest, and sometimes parents even help the cubs to be born by rolling the egg between the tongue and the palate.
The mother accompanies the hatched offspring to the pond or carries it in her mouth.
The sex of Nile crocodile cubs, like any other crocodiles, is formed under the influence of the temperature inside the nest during the second month of incubation: at temperatures from 31.7 to 34.5 degrees, males are born, in other cases females.
The length of newborn Nile crocodiles is approximately 28 cm, but in the first year of life the cubs develop quite quickly. By the end of the first year, crocodiles grow up to 60 cm in length, by two years - up to 90 cm. For two years, the female takes care of her offspring, sometimes together with other females, establishing something like a “nursery”, after which the grown individuals are about 1 .2 m leave their mother and, until puberty, avoid meeting with major representatives kind.
Young crocodiles dig holes up to 3.6 meters long in the banks, which serve as shelter for them until they are 5 years old. Adults also dig similar burrows for themselves under the roots of trees hanging over the water.